The goals for this year are (1) to elucidate the specific ionic channels controlling cardiac cell contractility by applying specific electrogenic drugs, (2) to induce contractile changes by drug and laser irradiation, and at the same time monitor the electrical activity of the cells, (3) to produce specific structural alterations by laser irradiation and correlate these changes with contractile and behavioral responses, (4) to elucidate further the role of stress fibers in heart endothelial cells, and to better understand the repair of these structures following laser microirradiation.